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TXB0102: TXB0102 Output can not achieve 5V, VCCB

Rocky Chen
Expert 6805 points
Part Number: TXB0102
Other Parts Discussed in Thread: CSD13201W10, SN74LVC2T45

Hi,

When using TXB0102 to drive MOS, it was found the output voltage of TXB0102 B-Side can only achieve 2.5V, not the 5V which is the VCCB. But when disconnect the MOS, the B side output can achieve 5V. I wondering to know if there is something not correct on schematic design. There is a 400k pull down resistor on B output.

Could you please help check? Thanks!

Best Regards

Rocky

  • 0
    Guru 244350 points
    TXB devices are designed to drive capacitive loads up to 70 pF, but the CSD13201W10 has a typical total gate charge of 2300 pF at 4.5 V. This means that the TXB's edge rate accelerators will no be active long enough, so you would need to wait for a much longer time for the gate being charged.

    How fast are you switching?

    The TXB has weak output drivers to allow bidirectional communication. But your circuit needs only unidirectional translation; consider using the SN74LVC2T45 instead.
  • 0
    TI__Intellectual 2100 points
    Hey Rocky,

    I have to agree with Clemens that the gate capacitance is probably be a problem for you, especially during fast switch cycles like PWM. Another issue to look at is the fact that you guys are using 4 N-Channel FETs with no high side driver. Typically this floats the high side FETs and you need another circuit to provide the proper potential.

    Nick